KR101188751B1 - Acryl-based retardation film with positive birefringence and liquid crystal display comprising the same - Google Patents

Abstract

The present invention relates to a retardation film having a positive retardation value and a liquid crystal display including the same. More specifically, the present invention provides a retardation film comprising 1) an acrylic copolymer comprising an acrylic monomer and an aromatic vinyl monomer, and 2) a rubber component, wherein the ratio of the thickness direction retardation value to the in-plane retardation value in one film. A retardation film for an IPS (In-Plane Switching) mode liquid crystal display device having a value of (R _th / R _in ) of 1 to 1.5, and an In-Plane Switching (IPS) mode liquid crystal display device including the same.

Retardation film, acrylic, rubber, stretching, IPS, liquid crystal display

Description

Acrylic retardation film having a positive birefringence and a liquid crystal display including the same {ACRYL-BASED RETARDATION FILM WITH POSITIVE BIREFRINGENCE AND LIQUID CRYSTAL DISPLAY COMPRISING THE SAME}

The present invention relates to an acryl-based retardation film having a positive birefringence and a liquid crystal display including the same.

Recently, display technologies using various methods such as plasma display panel (PDP) and liquid crystal display (LCD), which replace conventional CRTs, have been proposed and marketed based on the development of optical technology. Polymer materials for such displays are becoming more sophisticated. For example, in the case of liquid crystal displays, as thin film thickness, light weight, and large screen area are promoted, wide viewing angles, high contrast, suppression of image color tone change according to viewing angle, and uniformity of screen display have become particularly important problems.

Accordingly, various polymer films are used for polarizing films, retardation films, plastic substrates, light guide plates, and the like, and liquid crystals include twisted nematic (TN), super twisted nematic (STN), and VA (vertical alignment). ), Various types of liquid crystal display devices using IPS (in-plane switching) liquid crystal cells, etc. have been developed. All of these liquid crystal cells have an inherent liquid crystal array, have inherent optical anisotropy, and in order to compensate for this optical anisotropy, films have been proposed in which various kinds of polymers are drawn to give a retardation function.

As a method of manufacturing such a retardation film, after manufacturing various polymer films, there exist methods, such as longitudinal uniaxial stretching, step biaxial stretching, simultaneous biaxial stretching, etc.

The retardation film produced through the stretching process has a (+) retardation value in the in-plane retardation value and the thickness direction, and these films are applicable to the VA (Vertical Alignment) mode of the liquid crystal mode. Therefore, various patents have proposed the method of manufacturing the retardation film which has a retardation value of (+) in thickness direction.

For example, Japanese Unexamined Patent Application Publication No. 9-304619 is mentioned as an example using polycarbonate (PC) resin. A method for continuously producing a film having a phase difference value of (+) in the thickness direction by adhering a heat shrinkable film to a transparent film by a stretching method and heat treatment is disclosed. However, this method is a complicated process, it is difficult to increase the speed of the line for sufficient heat shrinkage of the film, there is a problem such as low productivity. Moreover, there exists a problem that the phase difference value of the surface direction and the thickness direction of the obtained film is irregular according to a film part.

Meanwhile, in the liquid crystal mode, an in-plane switching (IPS) mode requires a phase difference film having a positive phase difference value in the thickness direction, but most polymer films have molecules arranged in the stretching direction during stretching, and an in-plane phase difference value. It has a phase difference value of (+) in the thickness direction.

Thus, most retardation films applied to IPS (In-Plane Switching) mode liquid crystal display devices are manufactured by coating liquid crystal molecules having positive birefringence on a film having a retardation value of (−).

The present invention can provide a compensating effect of A-plate and positive C-plate with only one film drawn from an acrylic non-stretched film, and the phase difference value is not only uniform, but also preferable in-plane retardation value and phase difference value in thickness direction. An object of the present invention is to provide a retardation film for an IPS (In-Plane Switching) mode liquid crystal display device and an In-Plane Switching (IPS) mode liquid crystal device including the retardation film.

Accordingly,

1) an acrylic copolymer comprising an acrylic monomer and an aromatic vinyl monomer, and

2) rubber components

Including, the in-plane retardation value represented by the following equation 1 is 50 ~ 300nm, the thickness direction retardation value represented by the following equation 2 is 50 ~ 300nm, the ratio of the thickness direction retardation value to the in-plane retardation value Provided is a retardation film for an in-plane switching (IPS) mode liquid crystal display device having a (R _th / R _in ) of 1 to 1.5.

R _in = (N _x -N _y ) × d

R _th = (N _z -N _y ) × d

In Equation 1 and Equation 2,

N _x is a planar refractive index in the film stretching direction,

N _y is a planar refractive index in the vertical direction of the film stretching direction,

N _z is a refractive index in the film thickness direction,

d is the thickness of the film.

In addition,

a) preparing an unstretched film using an acrylic copolymer comprising an acrylic monomer and an aromatic vinyl monomer, and a rubber component, and

b) stretching the non-stretched film of step a)

Included, the in-plane retardation value represented by the equation (1) is 50 ~ 300nm, the thickness direction retardation value represented by the equation (2) is 50 ~ 300nm, the ratio of the thickness direction retardation value to the in-plane retardation value Provided is a method of manufacturing a retardation film for an in-plane switching (IPS) mode liquid crystal display device having a (R _th / R _in ) of 1 to 1.5.

In addition, the present invention provides an in-plane switching (IPS) mode liquid crystal display including the retardation film.

Through the present invention, it is possible to provide a retardation film having not only a uniform retardation value but also a preferable in-plane retardation value and a retardation value in the thickness direction, and particularly, having a retardation value of (+) in the thickness direction of the retardation film. It can be applied to IPS (in-plane switching) liquid crystal display.

Hereinafter, the present invention will be described in detail.

The retardation film according to the present invention comprises 1) an acrylic copolymer comprising an acrylic monomer and an aromatic vinyl monomer, and 2) a rubber component, wherein the ratio of the thickness retardation value to the in-plane retardation value (R _th / R _in ) It is characterized in that the retardation film for IPS (in-plane switching) mode liquid crystal display device having a 1 to 1.5.

In the retardation film according to the present invention, 1) the acrylic monomer of the acrylic copolymer is methyl methacrylate (methyl methacrylate), ethyl methacrylate (ethyl methacrylate), propyl methacrylate (propyl methacrylate), n-butyl N-butyl methacrylate, t-butyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, methoxy ethyl methacrylate methacrylate), ethoxyethyl methacrylate, butoxy methyl methacrylate, butoxy oligomers thereof, and the like may be used, but is not limited thereto.

In the retardation film according to the present invention, the content of the acryl-based monomer in the 1) acrylic copolymer is preferably 40 to 99% by weight, more preferably 50 to 98% by weight, and 60 to 97% by weight. Even more preferred. When the content of the acrylic monomer is less than 40% by weight, the high heat resistance and high transparency of the acrylic resin may not be sufficiently expressed, and when the content of the acrylic monomer exceeds 99% by weight, there may be a problem that the mechanical strength falls.

In the retardation film according to the present invention, examples of the aromatic vinyl monomer of the 1) acrylic copolymer include styrene, α-methyl styrene, 4-methyl styrene, and the like, but are preferably styrene, but are not limited thereto. .

In the retardation film according to the present invention, the content of the aromatic vinyl monomer in the 1) acrylic copolymer is preferably 1 to 60% by weight, more preferably more than 10% by weight and 60% by weight or less.

In the retardation film according to the present invention, when the aromatic vinyl monomers such as the styrene-based are stretched, the main chain of the styrene-based is oriented in the stretching direction, and the benzene ring (substituent) having a relatively high electron density is in the stretching direction. Oriented perpendicular to, it can be implemented to have the lowest value of the orientation refractive index in the stretching direction. For this reason, the retardation film which has a retardation value (+) value in the thickness direction can be manufactured.

1) When the content of the aromatic vinyl monomer in the acrylic copolymer is less than 10% by weight, since the phase difference value developed according to the elongation may be relatively high, stretching may be required. Therefore, the content of the aromatic vinyl monomer may be It is more preferable that it is more than 10 weight% and 60 weight% or less.

In the retardation film according to the present invention, the 1) acrylic copolymer may further include a maleic anhydride or maleimide monomer.

Examples of the maleic anhydride-based or maleimide-based monomers include maleic anhydride, maleimide, N-methyl maleimide, N-ethyl maleimide, N-propyl maleimide, N-isopropyl maleimide, and the like. It is not limited.

1) The content of the maleic anhydride or maleimide monomer in the acrylic copolymer is preferably 5 to 30% by weight, more preferably 5 to 10% by weight. When the content of the maleic anhydride-based or maleimide-based monomer exceeds 30% by weight, the brittleness of the film may increase, and thus the film may be easily broken.

In the case of an acrylic copolymer including an aromatic vinyl monomer, the glass transition temperature of the resin may be low, and thus there may be a problem in that it is vulnerable to heat resistance when manufacturing into a film. However, maleic anhydride or maleimide-based resin is included in the acrylic copolymer including the aromatic vinyl monomer. In the case of including the monomer, there is an advantage that can increase the heat resistance of the acrylic copolymer.

In the retardation film according to the present invention, the 1) acrylic copolymer is preferably a copolymer of an acrylic monomer and an aromatic vinyl monomer, and more preferably a copolymer of an acrylic monomer, an aromatic vinyl monomer, and a maleic anhydride monomer.

In the retardation film according to the present invention, the above 1) acrylic copolymer preferably has a glass transition temperature (T _g ) of 100 to 250 ° C, more preferably 110 to 250 ° C. The retardation film including the acrylic copolymer having the glass transition temperature (T _g ) of 100 to 250 ° C. may have excellent durability.

In the retardation film which concerns on this invention, it is preferable that the refractive index of said 1) acrylic copolymer is 1.480-1.550.

In the retardation film according to the present invention, the 2) rubber component is a thermoplastic resin composition having excellent transparency when the refractive index of the rubber component is similar to the refractive index of the 1) acrylic copolymer, so that the 1) acrylic copolymer The rubber component having a refractive index of 1.480 to 1.550 having a similar refractive index to is not particularly limited. More specifically, the rubber component 2 is preferably an acrylic rubber having a refractive index of 1.480 to 1.550, a rubber-acrylic graft core-shell polymer, or a mixture thereof, but is not limited thereto.

The acrylic rubber may include alkyl acrylates such as butyl acrylate and 2-ethyl hexyl acrylate. The rubber-acrylic graft core-shell polymer may be butadiene. (butadiene), butyl acrylate or butyl acrylate-co-styrene based rubber as the core, poly (methyl methacrylate, PMMA) or polystyrene Particles having a size of 50 to 400 nm and the like can be used.

In the retardation film according to the present invention, the content of the 2) rubber component is preferably 1 to 20 parts by weight, more preferably 1 to 15 parts by weight, more preferably 1 to 10 parts by weight based on 100 parts by weight of the 1) acrylic copolymer. Even more preferred is parts by weight. When the content of the rubber component is less than 1 part by weight, it is impossible to express excellent mechanical strength of the retardation film, the film is brittle and there is a problem in the processing process, and there is a problem that the optical performance is not sufficiently expressed. In addition, when the content exceeds 20 parts by weight, there is a problem that the high heat resistance and high transparency of the acrylic copolymer inherently are not sufficiently expressed, and processing problems such as haze may occur in the stretching process.

On the other hand, when the rubber component 2) includes a rubber-acrylic graft core-shell polymer as the rubber component, the content of the rubber-acrylic graft core-shell polymer is greater than 0 relative to 100 parts by weight of the 1) acrylic copolymer. It is preferable that it is below a weight part, It is more preferable that it is 0.5-7 weight part, It is further more preferable that it is 1-5 weight part.

The retardation film according to the present invention may further include additives such as UV absorbers, plasticizers, retardation enhancers, and the like.

1 type of said UV absorbers may be used, and 2 or more types may be used together. The UV absorbers include, but are not limited to, triazine-based UV absorbers, triazole-based UV absorbers, and HALS (hindered amine light stabilizer) -based UV absorbers. The triazine-based UV absorber may be commercially available Tinuvin 360, Tinuvin 1577 (Ciba Chemicals), Cyasorb UV-1164, Cyasorb UV-2908, Cyasorb UV-3346 (Cytec), etc. Tinuvin 384, Tinuvin 1130, Cyasorb UV-2337, Cyasorb UV-5411 and the like can be used as a HALS-based UV absorber Cyasorb UV-3853 and the like can be used.

As the plasticizer, plasticizers such as phosphate ester, carboxylic acid ester, phthalic acid and phosphoric acid may be used, and more specifically, triphenyl phosphate, phthalic acid ester, dimethyl phthalate, diethyl phthalate, diphenyl phthalate, and the like. Can be. The amount of the plasticizer may be added within a range that does not impair the physical properties of the retardation film, and the appropriate content is preferably 5 parts by weight or less with respect to 100 parts by weight of the acrylic copolymer.

The retardation synergist may be added to control the phase difference of the retardation film, a material having an aromatic ring is mainly used, the number of the aromatic ring is not particularly limited, but preferably about 2 to 6 is suitable. For example, trans-stilbene, diphenylacetylene, trans, trans-1,4-diphenyl-1,3-butadiene (trans, trans-1,4-diphenyl-1, 3-butadiene, biphenyl, fluorine, dibenzofuran, 2,7-dibromofluorene, carbazole, N-vinyl N-vinyl carbazole and the like can be used.

The content of the retardation synergist may vary depending on the desired retardation value and the amount of the additive and the stretching conditions within the limit that does not impair the optical properties of the retardation film, but 1) compared to 100 parts by weight of the acrylic copolymer Up to 10 parts by weight can be used.

In the retardation film according to the present invention, the in-plane retardation value represented by Equation 1 is 50 to 300 nm, and the thickness direction retardation value represented by Equation 2 is preferably 50 to 300 nm.

It is preferable that it is 50-300 nm, and, as for the said in-plane phase difference value, it is more preferable that it is 70-200 nm. When the in-plane retardation value is less than 50 nm, the optical properties required for the retardation film may not be expressed.

It is preferable that it is 50-300 nm, and, as for the said thickness direction retardation value, it is more preferable that it is 70-200 nm. When the thickness direction retardation value is less than 50 nm, excellent optical properties, which are the effects of the present invention, may not be expressed.

The retardation film according to the present invention preferably has a MD tensile strength of 70 N / mm ² or more, a TD tensile strength of 50 N / mm ² or more, a thermal expansion coefficient of 30 to 100 ppm / K, and a haze of 0.1 to 1.0%.

The tensile strength is preferably 70 N / mm ² or more, more preferably 75 N / mm ² , most preferably 80 N / mm ² or more with respect to MD, and preferably 50 N / mm ² with respect to TD. More preferably, it is 55 N / mm <^2> or more, Most preferably, it is 60 N / mm <^2> or more.

The thermal expansion coefficient is preferably 30 to 100 ppm / K, more preferably 30 to 90 ppm / K, and most preferably 30 to 80 ppm / K. When the thermal expansion coefficient exceeds 100 ppm / K, the polarization plate may be distorted, light leakage may occur due to a decrease in heat resistance and durability due to dimensional change at high temperature.

In addition, a method of manufacturing a phase difference film for an IPS (In-Plane Switching) mode liquid crystal display device according to the present invention includes a) manufacturing an unstretched film using an acrylic copolymer comprising an acrylic monomer and an aromatic vinyl monomer, and a rubber component. And b) stretching the unstretched film of step a).

In the method of manufacturing a phase difference film according to the present invention, the acrylic copolymer of step a) may further include maleic anhydride or maleimide monomer in the copolymer, and specific examples of the acrylic copolymer, rubber component, etc. Since the details are the same as the above, description thereof will be omitted.

In the retardation film production method according to the present invention, the method of manufacturing the unstretched film of step a) may use a solution casting method or an extrusion molding method.

The solution casting method is a method of manufacturing a film using a solution (dope) in which a material is dissolved in an organic solvent.

Examples of the organic solvent used in the solution casting method include halogenated hydrocarbons such as methylene chloride, chloroform, dichloroethane, acetone, methyl ethyl ketone, di Ketones such as ethyl ketone, cyclohexanone, di-isopropyl ether, tetrahydrofuran, 1,3-dioxane, 1 Ethers such as 1,4-dioxane, esters such as methyl acetate and ethyl acetate, dimethyl formamide, dimethyl acetamide Amide systems, such as these, etc. are mentioned, It is not limited to this.

In the solution casting method, the dope may be prepared by a general method known in the art. The dope may be prepared by adding 10 to 50% by weight of the solid resin such as the acrylic resin composition and the additive with respect to the organic solvent and stirring the solution. The production temperature is not particularly limited and can be adjusted according to the characteristics of the organic solvent. This solution may be prepared even under pressurized conditions.

The order of addition of each component is not particularly limited and may be produced under an inert gas such as nitrogen gas. The prepared dope can be passed through a coat hanger type T-die, cast into a chrome plating casting drum or belt, dried on a drying roll and wound up to produce a film.

In addition to the solution casting method, a method of manufacturing the unstretched film of step a) may be prepared by the following melt casting method.

The resin is dried in vacuo to remove moisture and dissolved oxygen, and then rubber components or other additives are added, and then the feed from the raw material hopper to the extruder is supplied to a nitrogen or single or twin extruder. Melt at high temperature to obtain raw material pellets, vacuum drying the obtained raw material pellets and melting them with a single extruder nitrogen-substituted from the raw material hopper to the extruder, passing them through a coat hanger type T-die, and then chrome plated casting rolls and drying rolls. It is possible to produce a film via.

The unstretched film prepared by the solution casting method or the extrusion molding method can obtain a desired phase difference through the b) stretching process. The stretching step may be performed in the longitudinal direction (MD) stretching or in the transverse direction (TD) stretching, or both. When extending | stretching both a longitudinal direction and a lateral direction, after extending | stretching either one, you can extend in another direction and you may extend | stretch both directions simultaneously. Stretching can be extended in one step or stretched in multiple steps. When extending | stretching in a longitudinal direction, extending | stretching by the speed difference between rolls can be performed, and when extending | stretching in a lateral direction, a tenter is used. The rail starting angle of the tenter is usually within 10 degrees, thereby suppressing a boeing phenomenon occurring in the lateral stretching and regularly controlling the angle of the optical axis. The same boeing suppression effect can also be obtained by making transverse stretching into multiple stages.

In the method of manufacturing a phase difference film according to the present invention, the method for stretching the b) unstretched film is preferably uniaxially stretched, but it is preferable to adjust the ratio of the width to the length of the stretch section of the film.

The b) stretching step will be described in detail as follows.

The longitudinal uniaxial stretching method according to the present invention can be carried out by performing a preheating step, a stretching step and a heat treatment step, respectively, which can be carried out continuously. The longitudinal uniaxial stretching method may be performed using a manufacturing apparatus provided in the order of a preheating zone, a stretching zone and a heat treatment zone.

The preheating step refers to a step of already heating and softening so that the unstretched film can be well stretched in the subsequent stretching step.

In the preheating step, when the glass transition temperature of the acrylic unstretched film is referred to as Tg, it is preferable to heat it so that it may become a fixed temperature in the range of (Tg-30 degreeC)-Tg. The preheating time is preferably 1 to 10 minutes, more preferably 1 to 5 minutes, in order to suppress the deformation more than necessary. If the film is sufficiently preheated in the preheating step, the film is softened sufficiently and there is little variation in the retardation value at the time of stretching.However, preheating for a long time requires a high magnification of the film due to the softening degree of the film, and it is difficult to express sufficient birefringence. do.

In the stretching step proceeding after the preheating step, it is preferable to uniaxially stretch the film in the advancing direction of the film in the temperature range of (Tg-20 ° C) to (Tg + 20 ° C) of the acrylic non-stretched film. Here, the stretching temperature, the stretching speed, and the draw ratio may be determined by the type, thickness, in-plane retardation value of the retardation film required, and the like. In such a longitudinal uniaxial stretching method, the stretching temperature is more preferably set to (Tg-10 ° C) to (Tg + 10 ° C) of the acrylic non-stretched film. When the stretching temperature is lower than (Tg-20 ° C) of the acrylic unstretched film, the phase difference deviation of the stretched film obtained by concentrating stress when stretching is tended to be large, and when the temperature is higher than (Tg + 20 ° C), the molecule The low degree of orientation makes it difficult to express birefringence.

In the manufacturing method of the retardation film which concerns on this invention, although the extending | stretching temperature in the said b) extending | stretching step changes with kinds of resin to be used, it is preferable that it is usually 80-250 ^o C, and it is more preferable that it is 100-200 ^o C. It is even more preferred that it is 120 ~ 180 ^° C.

In the b) stretching step, the draw ratio is set by the expression of the thickness of the unstretched film and the appropriate retardation value, but is preferably 1.1 to 3 times. When the draw ratio is lower than 1.1 times, it is difficult to obtain a film having a sufficient retardation value due to the low birefringence expressed. When the draw ratio exceeds 3 times, the deviation of the retardation value of the stretched film becomes large, and neck in There is an increasing problem.

In the b) stretching step, the stretching speed is preferably 10 ~ 500% / min.

In the b) stretching step, the ratio of the width to the length of the stretching section of the film is preferably less than 3, more preferably 0.5 to 3, and even more preferably 0.5 to 1.5.

In the present invention, by adjusting the ratio of the width to the length of the stretching section of the film can be adjusted the ratio (R _th / R _in ) of the thickness direction retardation value to the in-plane retardation value of the stretched film, the phase difference deviation of the film front Can be reduced to 5 nm or less.

As the ratio of the width to the length of the stretched region of the film is closer to 0.5 to 1.5, shrinkage in the width direction at the time of stretching is free, so that the thickness retardation value becomes equal to the in-plane retardation value.

Further, in the heat treatment step performed after the preheating step and the stretching step, the temperature of the film is (stretching temperature-50 ° C.) to (stretching) for the purpose of fixing the orientation of the longitudinal monoaxially stretched film in which the acrylic resin is the main component. Temperature-10 ℃) and then heat it.

When manufacturing the retardation film according to the present invention described above using a manufacturing apparatus provided in the order of preheating zone, stretching zone and heat treatment zone, the film transferred into the preheating zone, stretching zone and heat treatment zone is continuously heated and Although stretched and heat treated to cool, some intermediate temperature region may inevitably occur at the boundaries of these zones. As a means for reducing this intermediate temperature range as much as possible, although not particularly limited, a narrow slit-shaped passage can be provided where the film moves between the zones. In addition, the other section can maintain the temperature of each zone by a method of shielding with a heat insulating partition wall, a shielding with an air curtain, or a combination thereof.

As described above, the retardation film prepared according to the method of the present invention has an in-plane retardation value of 50 to 300 nm and a thickness retardation value of 50 to 300 nm at 550 nm, and a ratio of the thickness retardation value to the in-plane retardation value (R _th / R _in ) is 1-1.5, it is preferable that the width direction retardation deviation is 15 nm or less, and it is more preferable that it is 5 nm or less.

In addition, the present invention provides an IPS (In-Plane Switching) mode liquid crystal display including one or two or more retardation films.

An in-plane switching (IPS) mode liquid crystal display including one or two or more retardation films will be described in more detail as follows.

In the In-Plane Switching (IPS) mode liquid crystal display device comprising a liquid crystal cell and a first polarizing plate and a second polarizing plate respectively provided on both surfaces of the liquid crystal cell, the retardation film may comprise the liquid crystal cell and the first polarizing plate and / or It may be provided between the second polarizing plate. That is, a retardation film may be provided between the first polarizing plate and the liquid crystal cell, and one retardation film is provided between the second polarizing plate and the liquid crystal cell, or between the first polarizing plate and the liquid crystal cell and between the second polarizing plate and the liquid crystal cell. 2 or more It may be provided.

The first polarizing plate and the second polarizing plate may include a protective film on one or both surfaces. The inner protective film may include a triacetate cellulose (TAC) film, a polynorbornene-based film made of ring opening metathesis polymerization (ROMP), and a hydrogenated cyclic olefin-based polymer that is ring-opened polymerized. ring opening metathesis polymerization followed by hydrogenation) may be a polymer film, a polyester film, or a polynorbornene-based film made by addition polymerization. In addition, a protective film or the like made of a transparent polymer material may be used, but is not limited thereto.

The present invention also provides an integrated polarizing plate including a polarizing film and including the retardation film according to the present invention on one or both surfaces of the polarizing film as a protective film.

When the retardation film according to the present invention is provided only on one surface of the polarizing film, the other surface may be provided with a protective film known in the art.

As the polarizing film, a film made of polyvinyl alcohol (PVA) containing iodine or dichroic dye may be used. The polarizing film may be prepared by dyeing iodine or dichroic dye on a PVA film, but a method of manufacturing the same is not particularly limited. In the present specification, the polarizing film means a state not including a protective film, and the polarizing plate means a state including a polarizing film and a protective film.

In the integrated polarizing plate of the present invention, the protective film and the polarizing film may be laminated by a method known in the art.

For example, the lamination of the protective film and the polarizing film may be made by an adhesive method using an adhesive. That is, first, an adhesive is coated on the surface of the PVA film, which is a protective film of the polarizing film or a polarizing film, using a roll coater, a gravure coater, a bar coater, a knife coater or a capillary coater. Before the adhesive is completely dried, the protective film and the polarizing film are laminated by heat pressing at room temperature or pressing at room temperature. In the case of using a hot melt adhesive, a heat press roll should be used.

Adhesives that can be used when the protective film and the polarizing plate are laminated include one-component or two-component PVA adhesives, polyurethane adhesives, epoxy adhesives, styrene butadiene rubber (SBR) adhesives, or hot melt adhesives, but are not limited thereto. Do not. When using a polyurethane adhesive, it is preferable to use the polyurethane adhesive manufactured using the aliphatic isocyanate type compound which does not yellow by light. When using one-component or two-component dry laminate adhesives or adhesives with relatively low reactivity between isocyanates and hydroxyl groups, a solution-type adhesive diluted with an acetate solvent, a ketone solvent, an ether solvent, or an aromatic solvent, etc. You can also use At this time, it is preferable that adhesive viscosity is a low viscosity type of 5,000 cps or less. It is preferable that the adhesives have excellent storage stability and have a light transmittance of 90% or more at 400 to 800 nm.

A tackifier can also be used if it can exert sufficient adhesive force. It is preferable that the adhesive is sufficiently cured by heat or ultraviolet rays after lamination, and thus the mechanical strength is improved to the level of the adhesive. The adhesive strength is also large so that the adhesive does not peel off without breaking of either film to which the adhesive is attached. It is preferable.

Specific examples of the pressure-sensitive adhesive that can be used include natural rubber, synthetic rubber or elastomer having excellent optical transparency, a vinyl chloride / vinyl acetate copolymer, polyvinyl alkyl ether, polyacrylate or modified polyolefin-based pressure-sensitive adhesive, and a curing type in which a curing agent such as isocyanate is added thereto. An adhesive is mentioned.

In addition, the present invention provides an IPS (In-Plane Switching) mode liquid crystal display including the integrated polarizer.

Even when the In-Plane Switching (IPS) mode liquid crystal display device according to the present invention includes the aforementioned integrated polarizing plate, one or more retardation films according to the present invention may be further included between the polarizing plate and the liquid crystal cell.

Hereinafter, preferred embodiments of the present invention will be described in order to facilitate understanding of the present invention. However, the following examples are provided only for the purpose of easier understanding of the present invention, and the present invention is not limited thereto.

In addition, the measurements of the present invention were evaluated by the following analysis method.

[Phase difference]

The retardation of the film was measured at 10 ^o intervals from -50 ^o to +50 ^o in the extending direction and its vertical direction using AxoScan ^™ from Axometrics. The in-plane retardation and the thickness direction retardation are defined by R _in (in-plane retardation) and R _th (thickness retardation) _in Equations 1 and 2, respectively.

< Example  1 to 3>

Butyl acrylate-methyl methacrylate resin grafted core-shell with respect to 100 parts by weight of an acrylic copolymer (T _g = 129 ^° C) of 75% by weight of methyl methacrylate, 11% by weight of maleic anhydride and 14% by weight of styrene. 5 parts by weight of the polymer was fed to a 60 φ extruder in which nitrogen was substituted from the raw material hopper to the extruder and melted at 250 ^° C. to obtain raw pellets. The obtained raw pellets were vacuum dried and melted at 250 ^° C. with an extruder. A film having a film width of 500 mm and a thickness of 100 μm was produced by passing through a T-die of a coat hanger type and through a chrome plating casting roll, a drying roll, and the like. The prepared unstretched film was stretched 1.5 to 3 times at 120 ^o C under the condition of a line speed of 0.4 m / min. The ratio of the width of the film to the length of the stretching section during the stretching was adjusted to 0.5 to 3, which adjusted the distance between the rolls of the stretching section to produce a retardation film.

Experimental results such as retardation values are shown in Tables 1 and 2 below.

< Example  4 to 6>

Butyl acrylate-methyl methacrylate resin grafted core-shell polymer based on 100 parts by weight of an acrylic copolymer (T _g = 122 ° C.) of 72% by weight of methyl methacrylate, 13% by weight of maleic anhydride and 15% by weight of styrene. Except for using 3 parts by weight, a retardation film was prepared in the same manner as in Example 1. In addition, the film was stretched in the same manner as in Example 1 to implement a phase difference value.

Experimental results such as retardation values are shown in Tables 1 and 2 below.

< Comparative example  1>

JSR Corp. The Arton (product name, cyclo olefin polymer (COP)) unstretched film of the company was stretched in the same manner as in Examples 1 to 3 above to compare the phase difference values.

Experimental results such as retardation values are shown in Table 1 below.

Claims (26)

1) an acrylic copolymer comprising an acrylic monomer and an aromatic vinyl monomer, and 2) rubber components Including, the in-plane retardation value represented by the following equation 1 is 50 ~ 300nm, the thickness direction retardation value represented by the following equation 2 is 50 ~ 300nm, the ratio of the thickness direction retardation value to the in-plane retardation value Retardation film for in-plane switching (IPS) mode liquid crystal displays with (R _th / R _in ) of 1 to 1.5: [Equation 1] R _in = (N _x -N _y ) × d &Quot; (2) &quot; R _th = (N _z -N _y ) × d In Equation 1 and Equation 2, N _x is a planar refractive index in the film stretching direction, N _y is a planar refractive index in the vertical direction of the film stretching direction, N _z is a refractive index in the film thickness direction, d is the thickness of the film. The method according to claim 1, wherein 1) the acrylic monomer of the acrylic copolymer is methyl methacrylate (methyl methacrylate), ethyl methacrylate (ethyl methacrylate), propyl methacrylate (propyl methacrylate), n-butyl methacrylate (n -butyl methacrylate, t-butyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, methoxyethyl methacrylate, ethoxy Ethyl methacrylate (ethoxyethyl methacrylate), butoxy methyl methacrylate (butoxymethyl methacrylate), and a retardation film for IPS (in-plane switching) mode liquid crystal display, characterized in that selected from the group consisting of oligomers thereof. The retardation film of claim 1, wherein the content of the acrylic monomer in the acrylic copolymer is 40 to 99 wt%. The in-plane switching (IPS) mode liquid crystal display device of claim 1, wherein the aromatic vinyl monomer of the acrylic copolymer is selected from the group consisting of styrene, α-methyl styrene, and 4-methyl styrene. Retardation film. The retardation film of claim 1, wherein the content of the aromatic vinyl monomer in the acrylic copolymer is 1 to 60 wt%. The retardation film for an IPS (in-plane switching) mode liquid crystal display device according to claim 1, wherein the 1) acrylic copolymer is an acrylic copolymer further comprising a maleic anhydride or maleimide monomer in the copolymer. The group according to claim 6, wherein the maleic anhydride or maleimide monomer is composed of maleic anhydride, maleimide, N-methyl maleimide, N-ethyl maleimide, N-propyl maleimide, and N-isopropyl maleimide. Retardation film, characterized in that selected from. The retardation film for an IPS (in-plane switching) mode liquid crystal display device according to claim 6, wherein the content of the maleic anhydride or maleimide monomer in the acrylic copolymer is 5 to 30 wt%. The retardation film according to claim 1, wherein the glass transition temperature (T _g ) of the 1) acrylic copolymer is 100 to 250 ^° C. The retardation film for an in-plane switching (IPS) mode liquid crystal display device according to claim 1, wherein the 1) acrylic copolymer has a refractive index of 1.480 to 1.550. The retardation film for an in-plane switching (IPS) mode liquid crystal display device according to claim 1, wherein the 2) rubber component has a refractive index of 1.480 to 1.550. 2. The in-plane switching of claim 1, wherein the rubber component is selected from the group consisting of an acrylic rubber having a refractive index of 1.480 to 1.550, a rubber-acrylic-grafted core-shell polymer, and a mixture thereof. ) Retardation film for mode liquid crystal display devices. The in-plane switching (IPS) mode liquid crystal display device according to claim 12, wherein the rubber-acrylic graft core-shell polymer is present in an amount of more than 0 to 10 parts by weight based on 100 parts by weight of the acrylic copolymer. Retardation film. The retardation film for an IPS (in-plane switching) mode liquid crystal display device according to claim 1, wherein the rubber component is alkyl acrylate. The rubber component of claim 1, wherein the rubber component is made of butadiene or butyl acrylate as a core, and polymethyl methacrylate (PMMA) or polystyrene is used as a shell. A retardation film for an IPS (in-plane switching) mode liquid crystal display, characterized in that it is a rubber-acrylic graft type core-shell polymer which is a particle. The rubber component of claim 1, wherein the rubber component is based on a butyl acrylate-co-styrene-based rubber, and poly (methyl methacrylate) or polystyrene is used as a core. A retardation film for IPS (in-plane switching) mode liquid crystal display, characterized in that it is a rubber-acrylic-grafted core-shell polymer which is a particle having a size of (polystyrene) as a shell of 50 to 400 nm. The retardation film according to claim 1, wherein the content of the rubber component is 1 to 20 parts by weight based on 100 parts by weight of the 1) acrylic copolymer. 2. The IPS of claim 1, wherein the retardation film for in-plane switching mode liquid crystal display further comprises at least one additive selected from the group consisting of UV absorbers, plasticizers, and retardation enhancers. (in-plane switching) Retardation film for liquid crystal displays. a) preparing an unstretched film using an acrylic copolymer comprising an acrylic monomer and an aromatic vinyl monomer, and a rubber component, and b) stretching the non-stretched film of step a) so that the ratio of the width to the length of the stretching section is less than 3 Including, the in-plane retardation value represented by the following equation 1 is 50 ~ 300nm, the thickness direction retardation value represented by the following equation 2 is 50 ~ 300nm, the ratio of the thickness direction retardation value to the in-plane retardation value Method for manufacturing retardation film for IPS (in-plane switching) mode liquid crystal display with (R _th / R _in ) of 1 to 1.5: [Equation 1] R _in = (N _x -N _y ) × d &Quot; (2) &quot; R _th = (N _z -N _y ) × d In Equation 1 and Equation 2, N _x is a planar refractive index in the film stretching direction, N _y is a planar refractive index in the vertical direction of the film stretching direction, N _z is a refractive index in the film thickness direction, d is the thickness of the film. 20. The method for manufacturing a phase difference film for an in-plane switching (IPS) mode liquid crystal display device according to claim 19, wherein the b) stretching the unstretched film uses a longitudinal uniaxial stretching method. 20. The method of claim 19, wherein the b) stretching the unstretched film comprises a preheating step, a stretching step and a heat treatment step. The in-plane switching (IPS) mode of claim 19, wherein the b) the stretching temperature in the stretching step is 80 to 250 ^o C, the draw ratio is 1.1 to 3 times, and the stretching speed is 10 to 500% / min. The manufacturing method of retardation film for liquid crystal display devices. delete An in-plane switching (IPS) mode liquid crystal display device comprising one or two or more retardation films for the in-plane switching mode liquid crystal display device of claim 1. An integrated polarizing plate comprising a polarizing film, comprising a retardation film for an IPS (in-plane switching) mode liquid crystal display device of any one of claims 1 to 18 on one or both surfaces of the polarizing film. An in-plane switching (IPS) mode liquid crystal display comprising the integrated polarizer of claim 25.